How to make it

In a wide skillet, heat butter. Sweat onions and add mushrooms and saute over until deep golden, about 20 minutes. While this is cooking, blend broth, mustard, heavy cream and sour cream together. Lower heat, sprinkle flour over mushrooms and onions and cook, stirring for a minute. Whisk in liquids and simmer, without boiling until sauce thickens, about 5 minutes. Add meat to sauce and heat, without boiling until meat is just warmed through. Season to taste with salt and pepper; stir in dill and parsley and spoon over noodles.